To produce precise 3D parts or objects by 3D printing, calibration or alignment of the one or more dispensing (deposition or printing) heads (hereinafter also referred to as dispensing tips or nozzles, or dispensing tips/nozzles) is required. Alignment of one or more dispensing tips and a printing substrate, e.g., a build surface, is challenging due to the myriad of variables that may cause misalignment or position errors. More specifically, before initiation of a printing operation or job and during a printing operation, each tip opening of each dispensing tip is preferably aligned—and remains aligned—in the x-, y-, and z-dimensions of the build volume of the 3D printer. Moreover, when the 3D printer includes a deposition system having two or more deposition cartridges, each cartridge having its own dispensing tip, there is a relative offset distance from nominal for each dispensing tip.
Some conventional 3D printers rely on a factory-installed, mechanically fixed dispensing tip position, while others require manually adjusting each dispensing tip relative to the build surface, as well as to every other dispensing tip. Problematically, in most instances, x- and y-offsets between dispensing tip or nozzle locations are typically found experimentally, and the offset values are manually input into the path plan or other 3D printing software.
Typical methods for z-axis alignment and registration of dispensing tips may include manual adjustment, a physical switch that the tip touches, and/or mounting a sensor, e.g., a capacitive or inductive sensor, adjacent and proximate to the tip and aligning the sensor with or to the build surface. Disadvantageously, mounting a sensor requires precise factory calibration of the sensor with respect to the tip, which may be further affected when deposition cartridges are replaceable. Wear of the 3D printing system due to use, inadvertent impact of a tip, environmental temperature changes, and other factors may result in additional alignment and position errors.